Pakistani authorities claimed a moral victory Saturday after protests against their support for possible US military strikes on Afghanistan passed off largely peacefully, but violence in Karachi cast doubts on the port's use by US forces.

Less than 100,000 protestors took to the streets of Pakistan's main cities on Friday and there were no incidents of mass unrest to match the fiery rhetoric of the radical Islamists opposed to President Pervez Musharraf's stance in the present crisis.

Serious disturbances were limited to Karachi, where at least four people died as demonstrators clashed with police and tried to force businesses to shut down in line with their call for a general strike.

Police used tear gas and baton charges before opening fire on some of the stone-throwing militants. At least 100 arrests were made and 10 police officers injured.

"The majority of Pakistanis did not respond to the strike called by the so-called religious leaders," a government spokesman told AFP.

"The people of Pakistan have reposed their confidence in President Musharraf's policies," he added.

Musharraf announced last week that he would support possible military action against Afghanistan over the September 11 terror attacks on the United States.

The spokesman insisted the violence in Karachi had been instigated by a "small section" of demonstrators intent on fomenting unrest.

President Musharraf was set to chair a high-level meeting later Saturday of provincial governors, police chiefs and some military officials to review the internal security situation.

"The government is determined not to allow a minority to disturb public peace, and those responsible for violence in Karachi will be strongly taken to task," the spokesman said.

The Karachi incidents and the clearly high level of organization behind the demonstrations in the city, triggered speculation the protests were aimed less at Musharraf and more at preventing the port being used by US naval forces.

There have been reports that the US requests for help from Pakistan in preparing for possible strikes against Afghanistan included docking facilities in Karachi for US naval vessels.

The threat of US military action loomed larger after the ruling Taliban regime in Afghanistan on Friday rejected an ultimatum from US President George W. Bush to hand over the main suspect in the September 11 attacks -- Osama bin Laden -- or face the consequences.

"While the Pentagon may still be weighing the full potential of the ports in Karachi, some unknown forces have tried to swiftly turn Karachi into an Osama town," The News daily quoted a senior Karachi police official as saying.

The unidentified official said he was "intrigued" at the nature and scope of Friday's violence in the city.

More than 40,000 people had attended a rally Friday in the western district of Pakistan's biggest city, which is home to 10 million people.

In attacks on symbols of western influence, a cinema and a liquor store were torched and outlets of McDonalds and Kentucky Fried Chicken had their windows smashed while the crowd burned US flags and effigies of President Bush.

Some 10,000 turned out in Peshawar, 3,000 in Quetta and 1,500 in Islamabad, witnesses said.

Police in Quetta ordered foreigners to stay in their hotels but there were no reports of violence.

In Lahore, the leader of Pakistan's main Islamist party told a rally of 25,000 supporters to prepare to march on Islamabad if Musharraf stuck by his support for the United States.

There have been demonstrations every day since Musharraf announced his support for US military action -- ISLAMABAD (AFP)